The objective of this project is to investigate the functional properties of smooth muscle isolated from lungs of a.) normal animals, b.) animals exposed to chronic hypobaria (hypoxic hypoxia) and c) animals exposed to experimental asthma. The mechanical performance of isolated trachea and isolated pulmonary artery will be determined during isometric contractions induced by optimal electrical stimulation, drug stimulation (e.g., angiotension II) or antigen stimulation (sensitized isolated tracheal preparation). Spontaneous contractions of isolated trachea will be studied and the effects of temperature, pH conditions, acute O2 lack, as well as the effects of drugs and the effect of antigen-antibody reaction will be investigated. Intracellular electrical activities of airway smooth muscle will be investigated and the effects of different experimental conditions (such as pH, O2 lack and bronchoactive drugs) will be studied. Spontaneous activity of trachea will also be assessed in vivo, using a special extraluminal microstrain-gauge. The investigation of possible adaptive tissue changes of smooth muscle (airway and vascular) will be made in animals exposed to chronic hypobaria and in animals chronically exposed to asthmatic episodes.